Typewriting machine



P 1939. w. F. HELMOND 2,172,008

TYPEWR ITING MACHINE Filed May 8-, 1956 INVENTORL ATTd , Patented Sept. 1939.

UNITED STATES TYPEWRITING MACHINE William F. Helmond, West Hartford, Conn, as-

signor to Underwood Elliott Fisher Company, NewYork, N. Y., a corporation of Delaware Application May 8, 1936, Serial No. 78,560

16 Claims.

This invention relates to the platen-carriage of typewriting machines.

Fill-in work on government bid-forms or similar material, in which a number of ruled sheets are secured by fasteners which prevent the insertion of the work in the usual way, can be efliciently performed in a typewriter having a detachable platen, which permits the work-sheets to be set directly into the machine and the platen returned to position, thus eliminating the necessity of separating the sheets for individual insertion. A difficulty presented by such work-sheets,

however, is that the spacing of the lines does not always conform to the spacing established by the line-spacing mechanism of the typewriter, and

it has previously been necessary either to per- I form the work independently of the line-spacing control, or to readjust the work-sheet as each new line is being typed.

go It is an object of this invention to provide an improved platen-carriage in which the platen is releasably held by finger-operated clamps which are automatically locked against accidental opening or loosening. It is a further object to provide means effective to restrain the creeping or vibration-induced rotation of the platen when the normal platen-detent has been released, so that interlineated or other iractionally-linespaced work may be accurately performed.

In this invention, the platen-carriage endpieces have open-mouthed bearings to receive hearings in which the platen stub-shafts are journaled. Each end-piece is provided with a toggle-jointed platen-securing clamp comprising a finger-lever linked to a pivotally mounted keeper, theJatter being arranged to press downwardly on the platen-shaft bearings by manipulation of the finger-lever. Spring-actuated drawbolts are provided'to lockthe finger-levers in 40 platen-securing position.

To prevent platen-creeping when the line-space detent has been released to permit fractional line-spacing, there is provided an auxiliary detent including a brake-shoe arranged to engage a suitablebrake-drum on the platen-shaft, conjointly with the release of the line-space detent, thus permitting fractional line-spacing under positive control. v

' It is a feature of this invention that with the 50 clamp-operating finger-levers in platen-securing position, the pivot points of the toggle-jointed clamps are aligned to prevent the accidental breaking or relaxing of the said joints, and the said clamps are thus unyieldingly resistant to 55 upward pressure caused by the resistance of the bulky work-pack to confinement between the platen and the feed-rolls, or by the inertia of the platen-unit during the case-shifting movement thereof.

It is a second feature that because the platen- 5 clamps are in this manner self-locking, a comparatively loose engagement is permitted bev tween the draw-bolts and the finger-levers, and light compression springs are efiective to drive the said bolts into lever-locking position. 10

A third feature is that the platen-clamp locking-means require no adjustment, and the operation thereof, being unaflected by the vibration or jarring of the machine, is positive and uniform.

Other features and advantages will hereinafter 15 appear.

In the accompanying drawing,

Figure 1 is a fragmentary plan view of an Underwood typewriter, partly in section, showing details of the platen and platen-carriage con- 20 struction.

Figure '2 is a fragmentary end-elevation bf the carriage of Figure 1, illustrating the platenclampsand the line-space detents, the former in platen-securing position. 25

Figure 3, similar to Figure 2, shows the platen released for removal.

Figure 4 is an end-elevation of the carriage, illustrating the organization of the line-space feed and detent mechanism. 30

. Figure 5 illustrates the co-operative action of the normal and auxiliary line-space detents.

Figure 6 is a magnified view of the yoke-end of the clamp-operating lever, illustrating its cooperation with the draw-bolt in locking th 35 clamps in platen-securing position.

Figure 7 is an enlarged perspective, partly in section, of the draw-bolt and the associated clamp-operating lever.

End-pieces H) of a typewriter platen-carriage, Figure l, are spanned at the bottom by a transverse, grooved bar H, Figure 2, supported on anti-friction balls l2 within a co-operatively grooved runway Hi. It will be understood that the carriage may also include a paper-shelf, additional transverse tie-bars and main and upper feed-rolls, which have not been shownv in the drawing because they are of familiar design'and are unimportant as respects this invention. Each end-piece '50 may be provided with the usual ornamental mask, of which a side-wall H of the left-hand mask has been shown in section in Figure 1. Y

The platen-unit [5 includes an outer shell I6 overlying a cylindrical metal core I! into which end-pieces |8 are screw-threadedly inserted to the depth permitted by a gaging shoulder 20. Stub-shafts 2| are threaded into the said end pieces to a fixed depth. The left-hand stub-shaft 2|, Figure 1, passes through a hub or extension 22 of the left-hand end-piece l8, and is secured to the said hub by a set-screw 23. Knobs 24 are fixed to the stub-shafts.

A line-spacing ratchet 25 is arranged to cooperate with a line-space-feeding mechanism 26 (Figure 4)., a lever 21 and a pawl 28 of which are carried below the platen-shaft to permit the free removal of the'platen-unit. The ratchet 25 is formed on the outer surface of a brake-drum 30,

similar standardization of the center-to-center which comprises one element of a line-space release-clutch 3| for freeing the platen from the line-space-feeding mechanism. The drum 30 additionally co-operates with an auxiliary linespace detent, as later described. The said release-clutch, which in this invention is considered a part of the platen-unit I5, is disclosed in my Patent No. 1,432,695, issued October 17, 1922. The release-clutch includes a brake-shoe 32, Figure 1, which is normally in frictional contact with the inner surface of the brake-drum 3D to maintain an operative engagement between the drum 30 and the platen-shaft 2| so that the platen-unit may be rotated by the line-space feed 26. platen-unit I5 may be disconnected from the linespacing feed by drawing outwardly on a knob 33, which brings the brake-shoe 32 out of engagement with the said drum, all as described in my said prior patent.

A disk 34, Figure 1, also an element of the linespace reelase-clutch, is fixed to the left stubshaft 2| by a collar 35 and set-screw 36, and abuts against the end of the hub 22. At the right-hand stub-shaft, appropriate means are employed to establish the length of shaft between the collar 3! of the end-piece I8 and the hub 38 of the knob 25.

The right stub-shaft 2| and the hub 22 are smoothly machined to be freely rotatable within collar-like platen-bearings t0. Compression springs 4| urge the bearings Ml into contact with the disk 35 and the hub 38 at the left-and-right hand ends respectively of the platen.

The carriage end-pieces l0, which are preferably of cast metal, have open-mouthed bearings 42, Figure 3, in which the platen-bearings 40 are arranged to seat with a snug fit. The latter are provided with flanges 43 which slidably engage the sides of the end-pieces Hi.

It can be seen that the assembly of the platenunit l5 readily permits standardization of the span between the disk 35 and the hub 38, and a distance between the bearings 40. Thus, various types of platen-units l5, the printing surface characteristics of which may be suitable for various typing operations, may be used interchangeably with the same platen-carriage.

The platen-unit is releasably held within the platen-carriage by a platen-securing and release mechanism, hereinafter referred to as a "platenclamp, which is provided at each carriage-endpiece.

Each platen-clamp includes an operating lever 46, a keeper 61 and a link 38, all of which are shown to advantage in Figure 3. The lever 46, preferably of pressed metal, is pivotally secured to an extension 69 of the carriage-end-pieces H! by a rivet 50. As Figure 3 indicates, the arm 5| of the said lever is channel-shaped and as it is arranged to straddle the end-piece extension 49, it forms an attractive mask for the said end- The piece extensions. Grooves 5| are provided in the end-pieces ID to provide clearance for swinging the levers 46. A suitable finger-piece 53 is provided at the end of the lever 46, and overhangs the edge of the extension 49, as shown in Figure 2.

The keepers 6i, suitably pivoted to the endpieoes ID as at 55, include side-walls 55, spanned at the top by a web 56 which is arranged to overlie the platen-bearings 40. The web may be punched or drilled to accommodate a largeheaded machine-screw 51 adjustably held by the oppositely disposed nuts 58, 60. The heads 6| of the machine-screws 51 span the flanges 43 of the platen-bearings 40 and as the said flanges are of substantial strength, the downward pressure exerted by the keeper does not cause a distortion of the bearings 40, or an impairment of the free rotation of the platen-shafts therein.

The link 68, which pivotally connects the workarm 52 of the lever 46 and the keeper 41, engages the keeper at a point 59 intermediate its ends. The work-arm 52 and the link 48 form a togglejoint, and a counterclockwise rotation of the lever 46 causes a clockwise movement of the keeper.'

With the platen seated in the carriage-end-pieces H! as shown in Figures 1 and 2, a downward pressure on the levers 66 will cause the keepers to bear firmly down upon the platen-bearings 40, and the platen-unit I5 is held securely in o'perative position.

An abutment 62 is formed on the upper surface of each end-piece extension 49 to act as a stop for the operating levers. Suitable adjustment for wear or pressure standardization is provided by the adjustable mounting of the machine-screws 5T.

The operating levers 46 have a yoke-end 63 formed with a draw-bolt-receiving hole 64 and a restricted passage 55 to co-operate with a drawbolt 65 in looking the said levers in platensecuring position. The centers of the draw-bolts 56 and the holes 64 are circumferentially located with respect to the pivot points 50 of the levers 56, and the yokes 63 may be swung into and out of engagement with the draw-bolts.

The draw-bolts 68 are preferably cylindrical and have a head-portion 61 and a short neck 68, the latter being slightly smaller in diameter than the hole 64 of the yoke 63 but substantially larger than the width of the passage 65. Each drawbolt is slidably mounted on a machine-screw 10 which is inserted into the respective endpieces l0 and projects at right angles therefrom. It will be noted that the threaded portions of the screws 10 are smaller than the shanks thereof,

, draw-bolt 66, and reacts against a wall 13 thereofto drive the said draw-bolt into contact with the end-piece. It will be noted that the end-piece contacting edge of the neck 68 is slightly rounded; and it is preferable to provide the outer extremity of the draw-bolts with a grooved head It, to form a grip.

Each lever 46 may be provided with a stop 15, which, by striking a shoulder 16 formed in the associated end-piece, limits the clockwise rotation of said lever.

With the operatinglevers 46 in platen-securing the pivot 62. Lever 21 is held in normal position,

position, as shown in Figures 2 and 6, the yokes 63 'of the 'said levers encompass the necks 68 of the associated draw-bolts to an extent which prohibits upward movement of the levers 46 and the latter cannot be swung intoplaten-releasing position without first drawing the bolts out to bring the necks 68 clear'of the saidyokes, as shown in Figure 7. I

The platen-clamp-releasing operation is accomplished with little effort, preferably by drawing the bolts outwardly with the thumb and forefinger, and simultaneously pressing upward against the finger-pieces 53 with the middle finger. As shown in Figure-3, the keepers 41 are thereby swung completely out of the path of the platen-bearings, and the platen-unit I5 may be lifted directly out of the platen-carriage.

No adjustments of the draw-bolts are necessary, or, in fact, possible after the assembly of the device; they are free to turn on. thescrews 10, and the uniformity of operation of said bolts is unaffected by thevibration or shocks incident to the operation of the machine.

The operating levers 46 are relocked automatically as they are returned to the platen-clampsecuring position. As seen in Figures 6 and 7, the tips 11 of the yokes 63 are beveled inwardly. On the downward throw of the levers 46, the tips 11 contact the rounded edge of the necks 68 of the draw-bolts, and knife in between the necks and the end-plates, camming the draw-bolts outwardly against the action of the springs 12, and thus permitting the passages 65 to clear the shanks H of the screws 10. As the holes 64 come into position, the springs 12. drive the bolts inwardly, locking the levers in platen-securing position. It is obvious that nosimilar camming action can occur which would permit the release of the levers 46 by a mere upward pressure on the finger-pieces 53, because of the extent to which the yokes 63 encompass the necks 68 of the drawbolts;

As shown in Figure 2, the levers 46 and links 48 are so organized that with the levers in platensecuring position, the pivot-points 18 thereof spring to a position of slight overthrow with respect to the pivots 50 and 59 of thelevers 46 and keepers 41, respectively. The platen-securing clamps are in this manner self-locking; and the draw-bolts are called on merely to lock the clamp-operating levers 46 against accidental clamp-opening displacement. It is not essential,

therefore, that the draw-bolts 66 engage the yokes 63 with a tight fit, and the'springs 12 may drive the bolts home without obstruction.

From reference to Figure 4, it will be evident that the platen-line-spacing mechanism 26 and its associated detent-devices are organized in such manner as not to overlie the platen-unit or in any way interfere with its removal. Said line-space-feeding mechanism includes the usual line-spacing and carriage-return lever 19 pivotally mounted on an upper plate of the left-hand carriage-end-piece mask, all as indicated in dotted lines in Figure 4. An arm is associated with the lever 19 so as to be swung thereby, and bears against an arm 8| of the feed-pawl-operating lever 21 which, as shown, is carried beneath and. to the rear of the platen-shaft 2|. The lever 21 is pivotally mounted in spaced relationship with the wall I4 of the carriage-end-piece mask by a screw 82 and a collar 82*, and a rotation of the lever 19 'is thereby effective to swing the lever 21 in a counterclockwise direction about illustrated in Figure 4, by a suitable contractile lever 81 is pivotally secured to the mask side-wall I I, as at 88, and is arranged to be yieldably held in a plurality of operating positions 'through the co-operation of a spring-detent 90. The position of the lever 81 so controls the point of engagement of the pawl-head 83 with the ratchet 25 as to cause a rotation of the platen equivalent to one, two or three line-spaces in the familiar manner. A pin 9| is secured to the lower end of 1 the pawl 28 to co-operate with a toe 93 of the .pawl-operating lever 21 to prevent the excessive clockwise rotation of said pawl with respect-to the lever 21.

It is customary to provide a detent operative on the line-spacing ratchet to prevent platenrotation while typing, and to provide said detent with disengaging means to permit fractional linespacing. The detent-disengaging means should not be confused with the release-clutch 3i, previously refrered to. The release of the line-spacing detent from engagement with the ratchet does not disengage the latter from the platenshaft, and the platen may still be fully or fractionally line-spaced by manipulation of thelever 19. In this invention, an auxiliary detent is provided-which is brought into platen-restraining operation conjointly with the release of the linespace-ratchet detent, and control of the platen is maintained. 7

Referring to.Figures 2 and 4, a platen line-. space-detent rocker 95 is pivotally mounted intermediate its ends on the carriage-end-plate I0 by an eccentrically shouldered pivot-screw 91,

which permits an adjustment of the rocker 95 with respect to the platen-unit IS. A roller 98,

journaled between the side-pieces forming an arm 99 of the rocker, is normally held in yieldable platen-restraining contact with the teeth of the ratchet 25 through the action of a compressionspring I00, Figure 5; said spring being mounted within a bracket IOI fixed to said end-piece, and adjustable by a screw IOI Said spring presses against an arm I02 of said rocker, urging the latter into rotation counterclockwise of Figure 5, and bringing the roller 98 into engagement with said ratchet. g

A brake-shoeI03, Figure 2, preferably in the form of a finger of spring metal, is secured to a bracket I04, which may be formed. as an integral part of the rocker 95. It will be noted that the brake-shoe I03 and roller 98 are oppositely lo- 'cated. with respect to the pivot-screw 91, and a crank, is provided to cause a displacement of said rocker about its pivot 91. Said lever is pivoted to the end-piece ill on a large-headed screw I01 and pivotally connected to the detent-rocker by a link I08 engaging the rocker by a lostmotion, screw-and-slot connection H0, III, which pe mits the normal oscillatory movement of, the detent-rocker 95 during rotation of the platen.

A downward pressure on the knob N2 of the lever I06 causes a clockwise movement of the rocker 95, throwing the roller 98 out of engagement with the ratchet 25, thus freeing the platen from the normal line-space detent and conjointly bringing the brake-shoe I03 lnto frictional contact with the brake-drum 30. As illustrated in Figure 5, said brake-shoe is distorted by its contact with the drum, and the friction engendered by such contact is suflicient to restrain the accidental rotation of the platen when work is being performed independently of line-space control. The use of a single drum to accommodate the ratchet 25 and the necessary braking surface for co-operation with the brake-shoe I03 effects economies in manufacturing cost and provides a large-diameter brake-drum which increases the braking effect of said shoe. It'has been found unnecessary to provide the brake-shoe I03 with a frictional sleeve or coating, but such modification is within the scope of the invention.

It will be seen in Figure 5 that the link I08 has an ofiset H3 which is sufiicient to permit the pivot-point H4 of said link to overthrow the line of action between the screws I01 and H0, and the lever I06 is thereby held in release position against the pressure of the spring I00. The link I08, being in the same plane as the lever pivot-screw llll, abuts against said screw and limits the amount of rotation of said lever. Upward or clockwise rotation of the release-lever I06 is limited by a projection 5 formed in the link I08 to overlie the surface of the bracket IBI and to abut thereagainst to prevent the excessive rotation of said lever.

The clamps are effective to firmly seat the platen in the open bearings 42 against the tension of either the line-space-detent rocker 95, as seen in Figure 2, or the brake shoe I03, as seen in Figure 5.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim: 1. In a platen-carriage for a typewriting machine, having spaced end-pieces with openmouthed bearings arranged to receive platenshaft bearings, clamps arranged to hold said platen-shaft bearings releasably in the end-piece bearings, the said clamps comprising, in combination, a finger-lever, a pivoted keeper linked to the said finger-lever and arranged to bear upon the platen-shaft hearings or to be swung clear thereof bythe action of the said fingerlever to permit the removal of the platen'from the carriage, and a slidable locking-bolt arranged to co-operate with an open-ended yoke formed in the said finger-lever to lock the latter in. platen-securing position.

2. In a platen-carriage for a typewriting machine, having spaced end-pieces with openmouthed bearings arranged to receive platenshaft bearings, clamps arranged to hold said platen-shaft bearings releasably in the end piece bearings, the said clamps comprising, in combination, a finger-lever, a pivoted keeper linked to the said finger-lever and arranged to bear upon the platen-shaft bearings or to be swung clear thereof by the actionof the said finger-lever to permit the removal of the platen from the carriage, and a spring-actuated locking-bolt slidably mounted on the said end-pieces and arranged to co-operate with a yoke formed in the said fingerlever, the said yoke formed with a locking-boltreceiving opening and an edge-located passage to the said opening, the passage being substantially smaller than the diameter of the lockingbolt, means arranged to displace the locking-bolt to permit-the said yoke to pass the locking-bolt mounting asv the finger-lever is moved into platen-securing position, whereupon the bolt is spring-actuated into platen-securing engagement with the said yoke.

3. In a typewriting machine, the combination with a platen-carriage having open-mouthed bearings, a platen detachably mounted in said bearings and line-spacing and line-spacingdetent devices associated with the said platen, of platen-securing clamps pivotally mounted on the platen-carriage to hold the platen releasably in the said bearings, the said'clamps comprising a finger-lever, a keeper operatively associated with the said lever and arranged to be swung down against the platen' or upwardly away therefrom to hold or release the platen, means for securing the keeper against upward movement when in platen-securing position, and independent means for locking the finger-lever against accidental displacement.

4. In a typewriting machine, the combination with a platen-carriage having open-mouthed bearings, a platen detachably mounted in said bearings and line-spacing and line-spacingdetent devices associated with the said platen, of platen-securing clamps pivotally mounted on the platen-carriage end-pieces to hold the platen releasably in the said bearings, the said clamps comprising finger-levers, keepers pivoted to the said end-pieces adjacent the platen-bearings, and links operatively connecting the said keepers with the finger-levers, the keepers arranged to be swung into or out of platen-securing engagement with the platen by manipulation of the finger-levers, the organization of the lever, link and keeper of each clamp forming a toggle-joint in which the pivot points thereof are overthrown when the said clamp is in platen-securing position, thus preventing a force directed upwardly against the keeper from relaxing the said clamp.

5. In a typewriting machine, the combination with a platen-carriage having open mouthed bearings, a platen detachably mounted in said bearings and line-spacing and line-spacing-detent devices associated with the said platen, of platen-securing clamps pivotally mounted on the platen-carriage end-pieces to hold the platen releasably in the said bearings, the said clamps comprising finger-levers, keepers pivoted to the said end-pieces adjacent the platen-bearings, links operatively connecting the said keepers with the finger-levers, the keepers arranged to be swung into or outv of platen-securing engagement with theplaten by manipulation of the finger levers, the organization of the lever, link, and keeper of each clamp forming a toggle-joint in which the pivot-points thereof are overthrown when the said clamp is in platen-securing position, and locks operative on the finger-levers to prevent accidental, clamp-releasing movement of the said levers.

6. A platen-carriage for a typewriting machine,

including, in combination, spaced end-plates having open-mouthed bearings arranged to receive a platen, clamps co-operating with said end-plate bearings to hold the platen releasably therein, levers for operating the clamps, and spring-operated draw-bolts arranged to engage the clamp-operating levers to lock the said levers automatically in platen-securing position.

7. In a typewriter, an improved platen-carriage including a rotatable cylindrical platen mounted on axial shafting, bearings on each side of the carriage on which said shafting is detachably mounted,'clamps for frictionally engaging said shafting and locking said shafting on said bearings, said clamps being movable into and out of engaging position, finger-pieces for moving said clamps, said finger-pieces also looking said clamps unyieldably in the operative position, and means for automatically locking said fingerpieces in the operative position of the clamps.

8. A platen-carriage for a typewriting machine, including, in combination, spaced end-plates having open bearings arranged to rotatably support a platen, clamps co-operating with said endplate bearings to hold the platen detachably therein, levers for operating the clamps and spring-operated means arranged to engage the clamp-operating levers to lock said levers in platen-securing position automatically.

9. A platen-carriage for a typewriting machine, including, in combination, spaced end-plates having open bearings arranged to rotatably support a platen, clamps co-operating with said end-plate hearings to hold the platen detachably therein, levers for operating the clamps and spring-operated means arranged to engage the clamp-operating levers to lock said levers in platen-securing position automatically, said means being mounted on the outer sides of said end-plates.

10. A platen-carriage for a tabulating machine, including, in combination, spaced endplates having open bearings arranged to rotatably support a platen, clamps co-operating with said end-plate bearings to hold' the platen detachably therein, levers for operating the clamps and spring-operated draw-bolts arranged to engage the clamp-operating levers to lock the said levers in platen-securing position automatically, said draw-bolts being mounted opposite each other on the outsides of the end-plates of the carriage.

11. A platen-carriage for a tabulating machine, including, in combination, spaced endplates having open bearings arranged to rotatably support a platen, clamps co-operating with said end-plate bearings to hold the platen detachably therein, levers having finger-pieces for operating the clamps, and spring-operated draw-bolts arranged to engage the clampoperating levers to lock the said levers in platen-securing position automatically, said draw-bolts being mounted opposite each other on the outsides of the end-plates of the carriage, and below and in front of the ends of the finger-pieces whereby the draw-bolts may be gripped and pulled out readily by the middle finger and thumb of each hand, and the ends of the finger-pieces be lifted by the fore-finger of each hand simultaneously.

12. A platen-carriage for a typewriting ma.- chine, comprising, in combination, a support having an open hearing adapted to journal a platen, a keeper movable into and out of engageable position with the platen to retain same in said bearing and permit removal of the platen therefrom, and a linkage including articulated members pivoted on said support and said keeper respectively and having a stop in aligned condition, said linkage in aligned condition holding said keeper in engageing position and foldable to move said keeper free of the platen.

13. A platen-carriage for a typewriting machine, comprising, incombination, a support having an open bearing adapted to journal a platen, a keeper movable into and out of engageable position with the platen to retain same in said hearing and permit removal of the platen therefrom, a lever having a pivot on said support, a link having a pivot on said keeper and flexibly connected to said lever, and a stop for limiting movement of said lever in alignment with said link, said lever and link in aligned condition co-operating to hold saidkeeper in platen-engaging position and foldable to move said keeper free of the platen.

14. A platen-carriage for a typewriting machine, comprising, in combination, a support having'an open bearing adapted to journal a platen, a keeper movable into and out of engageable position with the platen to retain same in said bearing and permit removal of the platen therefrom, a lever having a pivot on said support, a link having a pivot on said keeper and flexibly connected to said lever, a stop for limiting movement of said,

lever in alignment with said link, said lever and link in aligned condition co-cperating to'hold said keeper in platen-engaging Position and foldable to move said keeper free of the platen, and means for automatically locking said lever in platen-retaining position.

15. A platen-carriage for a typewriting machine, comprising, in combination, a support having an open bearing adapted to journal a platen, a keeper movable into and out of engageable position with the platen to retain same in said bearing and permit removal of the platen therefrom, a lever having a pivot on said support, a link having a pivot on said keeper and flexibly connected to said lever, a stop for limiting movement of said lever in alignment with said link, said lever and link in aligned condition co-operating to hold said keeper in platen-engaging position and foldable to move said keeper free of the platen, said lever having a locking recess, and a retractible spring-pressed bolt arranged to engage said recess to hold said lever in effective position.

16. A platen-carriage for a typewriting machine, comprising, in combination, a support having an open bearing adapted to journal a platen, a keeper movable into and out of engageable position with the platen to retain same in said bearing and permit removal of the platen therefrom, and a linkage including articulated members pivoted on said support and said keeper respectively, and having a stop in aligned condition, said linkage in aligned condition holding said keeper in engaging position and foldable to movesaid keeper free of the platen, said keeper including a member adjustable relatively to the platen whereby to vary the efiect of said linkage.

WILLIAMF. HELMOND. 

